1. Field of the Invention
The invention relates to apparatus, systems, and methods for preventing the unwanted exposure of a device to an undesirable substance.
2. Description of Related Art
Various types of devices are subject to damage or other undesirable effects when exposed to particular substances. As used throughout this patent, including the appended claims, the term “undesirable substance” means any one or more fluid, liquid, particle, substance, or combination thereof that may damage, alter the performance, or otherwise affect a device in a way that is not desired. As used throughout this patent, including the appended claims, the term “device” means any one or more machine, material, media, instrument, other item, or arrangement or combination thereof, that is desired to be at least partially isolated, or shielded, from exposure to, or contact with, one or more undesirable substances. Non-limiting examples of devices are optical fibre, sensors, and optical fibre sensors.
Devices that are carried in, encased, or at least partially surrounded by, a carrier or barrier may still be at risk for potential exposure to undesirable substances. In the petroleum exploration and production industry, for example, optical fibre carried in cables is often used to link optical fibre sensors to measurement instrumentation, or as part of an optical fibre sensing system, such as a distributed temperature sensing system. Exposure of some types of optical fibre to certain substances, such as hydrogen gas, may cause undesirable degradation of the optical properties of the fibre, especially in high temperature applications. Thus, the entry of hydrogen into the cables can lead to problems. Because hydrogen is a very small molecule, it is capable of permeating typical cables and, consequently, contacting and negatively affecting the optical fibre.
Thus, there remains a need for methods, apparatus, and/or systems having one or more of the following attributes, capabilities, or features: prevents unwanted exposure of one or more devices to one or more undesirable substances; prevents the unwanted entry of undesirable substances into cables; precludes the permeation of hydrogen into optical fibre-bearing cables that causes undesirable degradation of optical properties of or damage to the optical fibre; utilizes readily available shield substances to isolate devices from unwanted contact with undesirable substances; is simple and cost effective to implement; can be implemented with existing technology and components; is cost effective and simple to retrofit or adapt existing technology; and is useful with devices located in harsh environments.